OK, been through this whole thread. A couple of observations: most of the pictures seem to be of carboys with glass a lot thinner than the old water company bottles I use.
I grew up in an area with almost undrinkable tap water, and everyone we knew had a water cooler sitting in the kitchen, with a 5 gallon bottle in it. In eighteen years, I don't remember ever seeing a broken one.
Sudden temperature changes aren't good for glass. I would never pour hot or cold liquid into a carboy, without pre-cooling or warming it first. It doesn't take that much of a temperature difference; I once had a room-temp beer mug crack when I stuck it under tap water to rinse it. It was winter ,and our water pipes weren't well-protected.
I'll continue using my old thick jugs. But I'll inspect them closely before each use; I'll be careful not to subject them to sudden temperature changes, or bounce them off hard surfaces and corners; I'll knock on wood every time I dig one out... and I thank the OP for a good cautionary thread.